1 /* e_coshf.c -- float version of e_cosh.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #ifndef lint 17 static char rcsid[] = "$FreeBSD$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 #ifdef __STDC__ 24 static const float one = 1.0, half=0.5, huge = 1.0e30; 25 #else 26 static float one = 1.0, half=0.5, huge = 1.0e30; 27 #endif 28 29 #ifdef __STDC__ 30 float __ieee754_coshf(float x) 31 #else 32 float __ieee754_coshf(x) 33 float x; 34 #endif 35 { 36 float t,w; 37 int32_t ix; 38 39 GET_FLOAT_WORD(ix,x); 40 ix &= 0x7fffffff; 41 42 /* x is INF or NaN */ 43 if(ix>=0x7f800000) return x*x; 44 45 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 46 if(ix<0x3eb17218) { 47 t = expm1f(fabsf(x)); 48 w = one+t; 49 if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ 50 return one+(t*t)/(w+w); 51 } 52 53 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ 54 if (ix < 0x41b00000) { 55 t = __ieee754_expf(fabsf(x)); 56 return half*t+half/t; 57 } 58 59 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ 60 if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x)); 61 62 /* |x| in [log(maxdouble), overflowthresold] */ 63 if (ix<=0x42b2d4fc) { 64 w = __ieee754_expf(half*fabsf(x)); 65 t = half*w; 66 return t*w; 67 } 68 69 /* |x| > overflowthresold, cosh(x) overflow */ 70 return huge*huge; 71 } 72